Locking formulas and constants from Sheet 1 in Sheet 2

Hi , I'm new here. I have searched the web and can't find what I'm looking for. This is what I need:

Sheet 1 has my recipe's costings, and how much I'm selling each product for and what profit each product will make, sheet 2 has the breakdowns of sales and profits. I have set the formulas and constants.

I work on a weekly basis in sheet 2. I want to lock week 1's formulas and constants.

For week 2 I copy and paste Week 1.

Here is my problem. As the price of food items keeps changing, I need to change the costing as it affects my profits. When I change the costing in Sheet 1, it still changes my profits in Sheet 2 for Week 1, AFTER I have locked it.

I hope this makes sense. For instance, week 1 garlic cost R8.00, in week 2 garlic is now R10.00, so it will affect my profits.

How do I lock week 1's cells with their formulas and constants from sheet 1, and still be able to change the costings on sheet 1 without affecting week 1's sales and profits?

Thanks in advance.